Glucose monitoring system
First Claim
1. A glucose monitoring system comprising:
- an enzymatic glucose sensor adapted to be positioned within a blood stream of a person whose blood glucose concentration is to be measured, said glucose sensor including means for generating a sensor signal that is inversely proportional to the concentration of sensed glucose in the blood stream, said glucose sensor comprising an oxygen detector that detects the amount of oxygen in a region of a prescribed enzyme held within said glucose sensor, and wherein glucose and oxygen in the blood stream react with said prescribed enzyme such that the amount of oxygen is inversely proportional to the glucose concentration, and wherein said oxygen detector comprisesa first working electrode (W1), a collector electrode (C), a reference electrode (R), and a second working electrode (W2), all of said first and second working electrodes, reference electrode and collector electrode being enclosed within a first membrane wherein an ionic solution is maintained, and said first membrane being enclosed within a second membrane,said prescribed enzyme being confined to a window region near said first working electrode,electrical means for causing an electrical current to flow between said collector electrode and said first and second working electrodes, andmeans for measuring how much current flows from said first and second working electrodes when a prescribed trim voltage is maintained across said reference electrode and said first and second working electrodes, the ratio of said currents comprising said sensor signal, which sensor signal provides a measure of oxygen in the blood stream in the vicinity of said glucose sensor; and
a glucose monitor electrically coupled to the glucose sensor, said monitor comprisingmeans for receiving the sensor signal,means for processing the sensor signal and generating a glucose concentration data signal therefrom,means for storing the glucose concentration data signal,means for monitoring the glucose concentration data signal over a prescribed period of time and generating a rate of change signal that indicates how rapidly the glucose concentration data signal is changing,means for selectively displaying the glucose concentration data signal and the rate of change signal,first alarm means for determining if the glucose concentration data signal exceeds a preset level limit, and if so, generating a first alarm signal,second alarm means for determining if the rate of change signal exceeds a preset trend limit, and if so, generating a second alarm signal,calibration means for periodically calibrating the sensor so that it provides an accurate measure of the glucose concentration in the blood stream, andcontrol means for controlling the monitor so that it performs at least one of a plurality of monitoring functions as selected by a user of said monitor.
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Accused Products
Abstract
A glucose monitoring system continuously measures the glucose concentration in a patient'"'"'s blood, provides an indication of the rate of change of such concentration, and determines whether the measured concentration and rate of change are within certain preset limits. If not, an audible and/or visual alarm signal is generated. The glucose monitoring system includes a glucose sensor adapted to be inserted into the venous system of the patient, where it responds to blood glucose and produces sensor signals related to the glucose concentration. The sensor signals are delivered through a suitable interconnect cable to a glucose monitor. In one embodiment, the interconnect cable includes a contactless connector that electrically isolates the glucose sensor from the monitor, and reduces the number of conductors required to interface with a plurality of sensors. The glucose monitor interprets the sensor signals by applying a previously determined calibration to quantitatively determine the blood glucose value. The blood glucose value thus determined is then processed in order to determine the rate of change, is stored (to create a history or record), and may also be displayed in large, easy-to-read numerals. Rate of change information (trend) may also be numerically or graphically displayed.
2120 Citations
28 Claims
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1. A glucose monitoring system comprising:
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an enzymatic glucose sensor adapted to be positioned within a blood stream of a person whose blood glucose concentration is to be measured, said glucose sensor including means for generating a sensor signal that is inversely proportional to the concentration of sensed glucose in the blood stream, said glucose sensor comprising an oxygen detector that detects the amount of oxygen in a region of a prescribed enzyme held within said glucose sensor, and wherein glucose and oxygen in the blood stream react with said prescribed enzyme such that the amount of oxygen is inversely proportional to the glucose concentration, and wherein said oxygen detector comprises a first working electrode (W1), a collector electrode (C), a reference electrode (R), and a second working electrode (W2), all of said first and second working electrodes, reference electrode and collector electrode being enclosed within a first membrane wherein an ionic solution is maintained, and said first membrane being enclosed within a second membrane, said prescribed enzyme being confined to a window region near said first working electrode, electrical means for causing an electrical current to flow between said collector electrode and said first and second working electrodes, and means for measuring how much current flows from said first and second working electrodes when a prescribed trim voltage is maintained across said reference electrode and said first and second working electrodes, the ratio of said currents comprising said sensor signal, which sensor signal provides a measure of oxygen in the blood stream in the vicinity of said glucose sensor; and a glucose monitor electrically coupled to the glucose sensor, said monitor comprising means for receiving the sensor signal, means for processing the sensor signal and generating a glucose concentration data signal therefrom, means for storing the glucose concentration data signal, means for monitoring the glucose concentration data signal over a prescribed period of time and generating a rate of change signal that indicates how rapidly the glucose concentration data signal is changing, means for selectively displaying the glucose concentration data signal and the rate of change signal, first alarm means for determining if the glucose concentration data signal exceeds a preset level limit, and if so, generating a first alarm signal, second alarm means for determining if the rate of change signal exceeds a preset trend limit, and if so, generating a second alarm signal, calibration means for periodically calibrating the sensor so that it provides an accurate measure of the glucose concentration in the blood stream, and control means for controlling the monitor so that it performs at least one of a plurality of monitoring functions as selected by a user of said monitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of measuring a glucose concentration in the blood of a patient comprising:
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(a) inserting a plurality of glucose sensor assemblies into a vein of a patient, each of said glucose sensors having a reference electrode, a collector electrode and first and second working electrodes; (b) applying a voltage to said electrodes so as to cause first and second electrical currents to flow through said first and second working electrodes, respectively, and measuring said first and second electrical currents, the ratio of said second electrical current to said first electrical current providing a measure of oxygen in the patient'"'"'s blood; (c) placing a glucose oxidase enzyme at said first working electrode, said glucose oxidase enzyme reacting with the oxygen and glucose in the blood such that the amount of oxygen measured at said first electrode is inversely proportional to the glucose concentration in the blood; (d) determining the glucose concentration in the blood based on said measure of oxygen and calibration constants associated with each of said glucose sensors; (e) comparing the glucose concentration measured by each of said plurality of sensors to determine if the respective plurality of glucose concentration measurements are within a prescribed of each other, and if so, combining the plurality of glucose concentration measurements to form a composite glucose measurement, and if not, rejecting the plurality of glucose measurements as being inaccurate; (f) storing the composite glucose measurement as a function of time; (g) computing a rate-of-change signal for the composite glucose measurement that indicates how said composite glucose measurement has varied over a specified period of time; (h) comparing the composite glucose measurement formed most recently and the rate-of-change signal to preprogrammed limits, and generating an alarm signal in the event the preprogrammed limits are exceeded; and (i) selectively displaying the composite glucose measurement and rate-of-change signal.
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25. A glucose monitoring system comprising:
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a glucose assembly comprising a plurality of glucose sensors, each glucose sensor comprising an enzymatic glucose sensor adapted to be positioned within a blood stream of a person whose blood glucose concentration is to be measured, each glucose sensor of the glucose assembly providing a respective sensor signal that varies as a function of sensed glucose in the blood stream; and a glucose monitor electrically coupled to the glucose assembly, said glucose monitor comprising means for receiving the sensor signal from each glucose sensor, means for processing the sensor signal received from each glucose sensor, said means for processing including means for comparing the sensor signals obtained from each of said plurality of sensors and generating a composite sensor signal only if the respective sensor signals are within a first prescribed amount of each other, means for storing the composite sensor signal, means for monitoring the composite sensor signal over a prescribed period of time and generating a rate of change signal that indicates how rapidly the composite sensor signal is changing, means for selectively displaying the composite sensor signal and the rate of change signal, first alarm means for determining if the composite sensor signal exceeds a preset level limit, and if so, generating a first alarm signal, second alarm means for determining if the rate of change signal exceeds a preset trend limit, and if so, generating a second alarm signal, calibration means for periodically verifying that each glucose sensor of the sensor assembly provides an accurate measure of the glucose concentration in the blood stream, and control means for controlling the monitor so that it performs at least one of a plurality of monitoring functions as selected by a user of said monitor. - View Dependent Claims (26, 27, 28)
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Specification